Simplify the following expression: $q = \dfrac{z}{5} - \dfrac{z}{6}$
Answer: In order to subtract expressions, they must have a common denominator. The smallest common denominator is the least common multiple of $5$ and $6$ $\lcm(5, 6) = 30$ $ q = \dfrac{6}{6} \cdot \dfrac{z}{5} - \dfrac{5}{5} \cdot \dfrac{z}{6} $ $q = \dfrac{6z}{30} - \dfrac{5z}{30}$ $q = \dfrac{6z -5z}{30}$ $q = \dfrac{z}{30}$